Process of producing clear stannic-chlorid solutions.



ermine PATENT orrron v .ELMEB a. smear, or Bn'ooKLYn, 1min YORK, assrenon T0 eornscniumr nnrrnnme .comrm, or new reen, N. Y., A. oonroiwrron or NEW JERSEY.

rnoonss or rnonuomo" CL AR- srANNIo-oHLomn SOLUTIONS.

Ho Drawing.

To all ,ivhom' it may concern: Be it known that I, ELMERA. SPERRY, a citizen of the United States, residingat Brooklyn, in the county of Queens and State of New York, have invented new and useful Improvements in the Process of Producmg Clear Aqueous Solutions from Anhydrous Stannic Chlorid, of which the following 1s a specification.

My invention relates to the process for roducing clear aqueous solutions from aniiydrous stannic chlorid and it consists of.

the details of procedure and etc s in the process hereinafter clearly set orth and pointedout in the claims. a

Difficulty has been experienced in at tempting to produce aqueous solutions from anhydrous or fuming stannic chlorid and in producing these solutions transparent, clear or brilliant as this quality is denominated. I-- have found that this difficulty arises from the great tendency of this material to decompose or hydrolyze 'in ,the resence of water in excess and also atv tie higher temperatures. It therefore arises also from the fact that the hydrated oxid of tin is a brilliantly white substance produced in an extremely high state of subdivision, the solutions being heavy and the solid being comparatively light the material readily remains in sus ension and impartsturbidity'or a cloude appearance to the solution. -For many uses this cloudiness is prohibitive and it therefore becomes portant to devise a process for producing solutions which can invariably be depended upon as being free from this serious defect. recess of pro ducing solutions: This consists in suitably preparing a clear starting solution, whlch after being prepared is continuously and I will now describe, my

carefully maintained at a density above the hydrolyzing point.

. I prefer to proceed in the following manv Specification of Letters Patent. Patented Aug. 23, 1910. Application fi d us t 190a. SerialIo. 448,437.

about 25% of the water, has been added.

If this process be performed in a vessel with non-metallic walls and especially of such a character as not to rapidly carry off the heat of formation, the hydrated SnCL will be found in its molten state. This is always} true when the temperature is above 80 C. ,or thereabout. The material once molten, will. however not congeal at a pointcon-' -siderably below this temperature. I now proceed under conditions of suitable agitation .and cooling to dilute this molten hydrate until a solution of about 25 B. is "obtained which may beconsidered as a suit-' able strength for the starting solution. I j have found that by awrong procedure it is very easy to cause this solution to become." milky, as above pointed out, and thus rendered unfit, in so far as it may be useful as astarting material for forming aclear solution of SnCl inasmuch as the milkiness .quickly disseminated throughout the'whole mass. I have found that a correct'procedure from this point is to add pure SnCl, to build I up the starting solution to the proper point, 1 usually between 60 and 7 O B. and afterward toadd water or weak working liquor 0" bath and then more fuming-ShCli-wr the heavy solution may be'added to the working bath up to the requirements ofthe particular skeins or. material under treatment. For the formation'oflarge quantities. of solution, water is added at this point preferably slowly to reducebut not to, or in fact anywhere near to the hydrolyzmg point of the material, whereupon more fum ing chlorid is added to strengthen the solution from this point and so on unt1l the requisite quantity of solution has been made up. Attention is called to the fact that this quantity is usually .in excess of the mime diate demand. The fact, is that'anexcess should exist, inasmuch as the excess is al- I Ways utilized for the starting point of the next batch or quantity.- A variation from this is permissible as follows, Instead of. the

alternate addition of fuming bichlorid andwater, theymay go on simultaneously but then only under conditions of more or less vigorous agitation and in different portions of the bath. Non-metallic walls are always 55 -ne'r: Beginning preferably. with a small preferable for this work and adeguateineans 50, which Thusit n be seminar-it is essential to start Wlthtlsolution-preferably containing more than 5% of tin, and srengthen; in

' adding water the solution must not fall to a 1 point. where hydrolyza-tion takes place at -"the. temperature' .at Which the solution 7 stands and this must be true at any local pint in the. solution, which is only avoided gy thorough mixing. The temperature of the solution should be kept below 105 C.

and? preferably should not be allowed to exceed frOmSO' to 90 Cain temperature and furthermore it is usually made in excess of the demand the excess being utilized as a starting' solution for a succeeding, batch orquantity',

,As an alternate proceeding to the above, it: may be stated thatthe' fuming bichlorid i may be added directly to the working bath but even here some water must be added to Imake up for-the loss iii Water in the solution removed with-the ske'ins oryarn, all under r conditions of temperature control. It will be observed, however, that the operation outlined above. is thus reproduced'inasmuch as 4 the density of the excess bathremaining ever must always exceed the hydrolyzing j point, so as to be fit for the starting soluthe bath,

tion andthe water is also added t either directly-orin'the formof Sn(]l solution, so that'thi's alternate proceeding falls distinctly within the process above fully de- ';,4.0 scribed. p

q 1 All aqueous solutions of stannic chlorid ,wh-ich' are above or are not sufiiciently di'-.

, 'luted to, reach the hydrolyzing point or a degree of concentration of the solution at i Wl1l Ch insoluble tin compounds are produced :at the working temperature, are, for the purposes of this'specification, denomi nated strong solutions.

I In and about chemical works the water less'of the ingredients to be-employed' and though to all intents and purposesthis'is' water, yet speaking accurately and in a technical sense, it is a weak solutionwhich may beiunderstood as complying with the terms of this issue and the invention extends to such use ',;The process having thus been fully described, it will be readily understoodthat '60, the ordinary variations, .such as are dic.

ta-ted by the peculiar materials to be treated used often may contain in solution conditions of temperature control, and keepor conditions of practice obtaining at the time or in the locality where it is practiced, may be employed without de artlng from the spirit of the invention as defined in the claims.

I I claim:

' 1,-The process of-producing clear aqueous solutions from anhydrous stannic chlorid, which consists in adding fuming stannic chlorid toa strong aqueous solution of stan- ,nic chlorid.

ing stannic chlorid and water to a strong aqueous solution of stannic chlorid under ing theconcentration ot' the solution above that at which insoluble tin compounds are produced at the temperature.

. 5. The process of producing clear aqueou solutions from anhydrous stannic chlorid, which consis'tsin alternately adding fuming stannic chlorid and waterito a strong aqueous solution of stannic chlorid while regulating the temperature, and preventingth'e solution from falling to a point below 3% tin content. I v

. 6. The process of producing clear aqueous solutions from anhydrous stannic chlorid, which consists in alternately adding fuming stannic chlorid and water in this order to a strong aqueous solution of stannic chlorid, while regulating the temperature.

7. The process of producing clear aqueous solutions from anhydrous stannic chlorid, which consists in alternatelyfiadding fuming stannic chlorid and-water to a strong aque ous solution of stannicchlorid, keeping the concentration of the solution above that at which insoluble tin compounds are produced at the temperature, continuing the 115 process until an excess of solution has aocumulated and utilizing such excess as a starting material in repeating the process.

ELMER A. SPERRY. iVitnessesz- ALICE l\IA'1'IUILATH, THOMAS F. EGAN. 

